The present invention relates to an apparatus and a method for analyzing body composition based on bioelectrical impedance analysis (BIA). More particularly, the present invention relates to an apparatus and a method for analyzing body composition using a hand electrode apparatus for improving the precision in measuring the upper body impedance by passing a weak, alternating current across the body through the current electrodes and reading the voltage difference.
A human body is composed of water, protein, bone, and fat, in addition to a small amount of special components. The total of these elements constitutes the body weight. Quantitatively measuring the respective elements is called body composition analysis. Recent years body composition analyzers have been actively developed due to interest in health care from fatness. The proportion occupied by the fat is called fatness and is used in diagnosing various adult diseases. Especially, the water portion is the main component for supporting the human body and the amount thereof is related to the amount of muscle generating energies. Thus, the amount of muscle in body is applied widely as an index indicating nutritive conditions. In the medical terms, patients suffering from malnutrition related, for example, to cancer are subjected to a periodically measuring the amount of muscle in body to determine remission state or to monitor progress of the disease. Further, the growth in child body and the nutrition status of elderly men can be diagnosed on basis of the analysis of the amount of muscle. Accordingly, an analysis of the body composition has been used as basic means to examine a person and needs for the precision in measuring the body composition have been increased. As one of conventional methods for measuring the body composition, bioelectrical impedance analysis (BIA) is widely employed. This method has advantages such as safety, fastness, and low cost in comparison with the other conventional methods. This method is carried out the following manner. That is, a weak alternating current is passed across the human body to analyze the body composition by measuring the electrical resistance or the impedance of the body.
A basic principle to measure the body composition by using BIA, is as follows: where rich in water, a weak alternating current flows easily so that a low resistance value is obtained. While, where insufficient in water the current is difficult to flow so that a high resistance value is obtained. As muscle contains the most water in the body, each amount of muscle and body fat may be measured on the above-mentioned principle. The apparatus for analyzing the human composition substitutes body height, weight, age, gender, and measured impedance of the human subject into the specific expression to calculate the body composition, and displays the analyzed results on the LCD display unit.
FIG. 1 shows the conventional embodiment of determining the upper body composition by measuring the impedance between both hands. As shown In FIG. 1(a), a person in an upright posture grasps a pair of electrodes comprising a left electrode and a right electrode, with arms stretched to the front. In the embodiment, upper palm electrodes 5, 7 contact with the upper part of a palm and fingers, and lower palm electrodes 6, 8 contact with the lower part of a palm and fingers, and the human subject locates the center of hands on the boundary between the upper hand electrode and the lower hand electrode to contact with the current electrode and the voltage electrode. As shown in FIG. 1(c), the electrodes contact with the palm and the fingers to be connected electrically with the body. However, the method has the disadvantage that the variation in the contact location between the electrode and the body depends on the grip posture and the change of contact area between the electrode and the body depends on the grip intensity, resulting in a low reproducibility of the measurement.
FIG. 2 represents another embodiment of determining the upper body composition by measuring the impedance between the right and left hand. The human subject grasps a column-shaped current electrode on the right and left side of the apparatus and contacts the right and left wrist on a voltage measuring electrode. The apparatus passes the electric current across the body through the column-shaped electrode and reads voltage differences between wrist electrodes used as the voltage electrodes. However, some variations in the contact location and the contact region are inevitable even for the same person, which results in a low reproducibility of the measurement. Further, the individual difference in the body size, for example the difference in arm length between an adult and a child, raises the deviation of the contact location.
In the prior arts, the accuracy and reproducibility of measurement highly count on how to grip the electrodes when the measurement is carried out for the untrained person. Thus, variations in contact location and contact region are inevitable and affect the measured value.
The present inventor developed an apparatus for analyzing body composition based on bioelectrical impedance analysis, which is disclosed in U.S. Pat. No, 5,720,296 and Korean patent No. 123,408 and No. 161,602. The inventions improve the accuracy in analyzing the body composition and can measure segmental impedances by using an electronic switch which is controlled by a micro-processor. However, the apparatus has disadvantages in portability.
Thus, in the method measuring the impedance between two arms by measuring the voltage difference between the voltage electrodes, the present inventor has invented an apparatus for analyzing body composition, which can improve the precision by minimizing factors to affect measurement results, when measurement is carried out repeatedly for individuals or the same person without a specially trained examiner.
An object of the present invention is to provide an apparatus for analyzing upper body composition, in which the upper body composition can be analyzed conveniently by passing an electric current across the body through the current electrodes and measuring the impedance between voltage electrodes.
Another object of the present invention is to provide an apparatus for measuring the upper body composition in which if palm electrodes are used as a current electrode, then thumb electrodes are used as a voltage electrode, and if thumb electrodes are used as a current electrode, then palm electrodes are used as a voltage electrode, so as to improve accuracy and reproducibility in the measurement.
A further object of the present invention is to provide a simple and portable apparatus for measuring the body composition which uses only hand electrodes to measure the upper body impedance.
A further object of the present invention is to apply the electrode method, in which a measuring person grips column electrode and contacts his thumbs to thumb electrodes, to other apparatuses measuring the upper body impedances.
The above objects and other advantages of the present invention will be apparent from the ensuing disclosure and appended claims.
A handle-shaped apparatus for analyzing the body composition based on the bioelectrical impedance analysis according to the present invention comprises: a right palm electrode 1 and a left palm electrode 3 located on the right and left side of said apparatus, contacting with each inner surface of the right and left palm and fingers excluding a thumb; a right thumb electrode 2 and a left thumb electrode 4 located by the side of said palm electrodes, so that a measuring person can grasp said palm electrodes and contact said thumb electrodes with the right and left thumbs; an impedance measuring circuit 15 for measuring the impedance based on a voltage-current ratio by making an alternating current flow between two of the electrodes with a current generator 13 therein and reading the voltage difference with a voltage meter 14 therein; an amplifier 16 and A/D converter 17 for interfacing the impedance measuring circuit 15, to a microprocessor; a keyboard 18 to input the body height, weight, gender, and age; the microprocessor 19 processing the data received from the impedance measuring circuit 15 and the keyboard 18; and a display unit 20 for to display the results processed by the microprocessor 19, thereby the apparatus locates voltage electrodes outside of the current pathway to measure the upper body impedances, highly reproducibly irrespective of the grip posture and grip intensity. In the body composition analyzing apparatus of the present invention, the results processed by the microprocessor are shown on the display.
The apparatus of this invention may be equipped with an interface for connecting an outside computer.